Integrated circuits are an integral part of any electronic device. A variety of integrated circuits are often used together to enable the operation of the electronic device. While integrated circuits are typically designed for a particular application, certain integrated circuits may have configurable logic.
For example, an application specific integrated circuit (ASIC) may have portions comprising configurable logic. Another type of integrated circuit which has configurable logic is a programmable logic device (PLD). A programmable logic device is designed to be user-programmable so that users may implement logic designs of their choices. One type of programmable logic device is a Complex Programmable Logic Device (CPLD). A CPLD includes two or more “function blocks” having a two-level AND/OR structure connected together and to input/output (I/O) resources by an interconnect switch matrix. Another type of programmable logic device is a field programmable gate array (FPGA). In a typical FPGA, an array of configurable logic blocks (CLBs) is coupled to programmable input/output blocks (IOBs). The CLBs and IOBs are interconnected by a hierarchy of programmable routing resources. For both of these types of programmable logic devices, the functionality of the device is controlled by configuration data bits of a configuration bitstream provided to the device for that purpose. The configuration data bits may be stored in volatile memory (e.g., static memory cells, as in FPGAs and some CPLDs), in non-volatile memory (e.g., FLASH memory, as in some CPLDs), or in any other type of memory cell. However, reset schemes for individual circuits implemented by the configuration bitstream may vary. Some require a global asynchronous reset, and make it synchronous within the core, while others may require a synchronous reset. Other circuits may employ a bus reset as their reset input. Other circuits such as an embedded processor may make reset requests. Accordingly, reset circuits within an integrated circuit may vary greatly.